1. Field of the Invention
The present invention relates, in general, to ultra-wideband signal generators, and more particularly, to technology related to a scheme for asynchronously regulating the equivalent half circuits of each of the differential pulse oscillators, and configuring the differential pulse oscillators into the form of an array for the purpose of generating multi-phase pulses and performing Phase Shift Keying (PSK) modulation when ultra-wideband signals are generated using the differential pulse oscillators and an array thereof.
2. Description of the Related Art
Ultra-wideband radio technology enables low-power operations due to a short pulse operation, and enables the implementation of a position tracking system requiring high-speed communication or high precision through the use of a wide bandwidth, and thus, research into ultra-wideband radio technology has recently been actively conducted. When transmission or reception is performed using a pulse, several problems occur due to the interference between signals or the periodic repetition of a pulse unless the pulse is modulated. In order to effectively transmit data and extract target information in a radar system or a communication system, at least Quadrature Phase Shift Keying (QPSK) or M-ary phase shift keying (M-PSK) is required.
As shown in FIG. 1, a conventional process of generating an ultra-wideband pulse and modulating the pulse using Binary Phase Shift Keying (BPSK) modulation is performed to generate ultra-wideband signals 104a and 104b in such a way as to allow signals 101a and 101b output from a differential sine wave generator 101, which is continuously operating, to pass through relevant switches only for a predetermined time (τ), using switches 102 and 103 and switch control signals 102a and 103a. 
Here, when the sine wave generator 101 has a differential structure, oscillation signals 101a and 101b have phases of (+) and (−). Accordingly, when signals are output using the switch 102 corresponding to a positive (+) signal, the signal at an output terminal 104 is a positive (+) pulse 104a. Further, when signals are output using the switch 103 corresponding to a negative (−) signal, the signal at the output terminal 104 is a negative (−) pulse 104b. Through this operation, BPSK modulation may be performed.
As shown in FIG. 2, a conventional process of generating an ultra-wideband pulse and modulating the pulse using QPSK is performed to generate ultra-wideband signals 208, 209, 210 and 211 in such a way as to allow signals 201a, 201b, 201c, and 201d output from a quadrature sine wave generator 201, which is continuously operating, to pass through relevant switches only for a predetermined period of time (τ) using switches 202, 203, 204 and 205 and a switch control signal 207. In this case, as shown in FIG. 2, the quadrature sine wave generator 201 may be implemented as an array of two differential oscillators and four inverting amplifiers.
The oscillation signals 201a, 201b, 201c and 201d of the quadrature sine wave generator 201 have phases of 0°, 90°, 180° and 270°, respectively. Therefore, when a signal is output using the switch 202 corresponding to a signal having a phase of 0°, the signal at an output terminal 206 is a pulse 208 having a phase of 0°. Further, when a signal is output using the switch 203 corresponding to a signal having a phase of 90°, the signal at the output terminal 206 is a pulse 209 having a phase of 90°. When a signal is output using the switch 204 corresponding to a signal having a phase of 180°, the signal at the output terminal 206 is a pulse 210 having a phase of 180°. When a signal is output using the switch 205 corresponding to a signal having a phase of 270°, the signal at the output terminal 206 is a pulse 211 having a phase of 270°. Therefore, when these pulses are used, QPSK modulation can be performed.
Such a conventional ultra-wideband pulse generator is problematic in that power efficiency deteriorates due to the insertion loss of the switch units 102, 103, 202, 203, 204, and 205, and in that additional power loss may occur when the switch units are implemented in the form of active amplifiers so as to compensate for the insertion loss of the switch units.